Pm-932 vs PM-30

Djl338

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Hi everyone
New to the forum, been doing lots of searches, reading and learning. I currently own a microlux mill, 3/4 hp brushless dc motor which I like, installed a dro and power feed, also things I’m thinking I really need. The downside is there’s not enough “real estate” for some projects. Most of what I do is automotive, vintage restorations making NLA parts, fittings Boring carbs etc, threading .Aluminum and mild steel materials. I’ve been reading through the posts from owners with both machines and it’s a hard decision, I really like dialing in the r.p.m. the microlux peaks at 2600 r.p.m., not so-much torque at the Lower speeds but does ok.
Seems like the 932 has lots of features for the money and at 1000+ lbs assume it’s a fairly stable machine, power down feed installed is also a plus for me, not sure about the r.p.m. Limitations for aluminum or if that’s even a concern. On the PM-30, also has some nice features, belt drive is the real plus for me, but they’re out of stock for a while, I can wait.I’ve read of some VFD mods on the 932 but not sure I want to go down that road and don’t want to void a really nice 3-year warranty.
Any advice fro the experts?, I’m not a machinist, and haven’t worked a full-size mill so have a minimal database on personal knowledge.
BTW everyone on this forum seems really nice, respectful, helpful and not condescending which is really makes this forum a pleasure to read and learn and unique among others.
Thanks again
David
 
Im not an expert, but maybe I can help compare the two.

The PM-30 has a 2 HP brushless motor which is variable speed, while the PM-932 is single speed with gears. The gearing means the 932 will have the motor running at its peak torque all the time, so the lower speeds won't lose torque the same way the PM-30 would. For manual machining, that may be the better option, since a lot of the cutting happens at lower speeds.

In terms of spindle speed, on a manual machine, I don't think the lower spindle speed is a huge deal. On a CNC, you really do want a higher speed spindle for working in aluminum, but you won't get there with a manual typically. For example, at 1970 RPM, 3 flutes, and .005 IPT, you need to get it moving at 30 IPM. That's not generally going to happen without CNC.

You mentioned the power down feed which I think would be a nice option, but that also adds $800 to the price. You could probably add a power down feed to either one for a lot less.

The two are about 300 lbs difference when you don't count the base. I don't think the base weight adds a ton to the machines rigidity, so I wouldn't consider it. The PM-30 also has more travels compared to the 930. That means the 930 will be more rigid since it is heavier and has less travel. For manual work, I would find that preferable, so long as you don't need the extra space. When cutting manually, I prefer bigger cuts going slower, so it would need the extra rigidity.

I hope that helps a little.
 
Shooter, thanks! , that more than helpful, it’s a great comparison and brought up things I didn’t think about or know, which at my stage is minimal. The point about the motor on the 932 running at peak torque at all times sort-of sways me in that direction. I saw a couple of YouTube’s with guys using a PDF for boring and seemed like a nice feature, but as you pointed out, a fairly expensive feature. I don’t plan on adapting to CNC so no worries there, Again, thanks for taking the time to compare these machines.
David
 
"You mentioned the power down feed which I think would be a nice option, but that also adds $800 to the price. You could probably add a power down feed to either one for a lot less."

Doesn't the PM932 with the power down feed also include power X and Z?
 
"You mentioned the power down feed which I think would be a nice option, but that also adds $800 to the price. You could probably add a power down feed to either one for a lot less."

Doesn't the PM932 with the power down feed also include power X and Z?

Yes it looks like it does. I missed that. I thought the positioning motor was standard on all of them and the X axis power feed was an extra.
 
Bill, there’s a 5-option menu, from basic to space shuttle version, but I also didn’t realize the Power down feed included the other axes... little less painful when I look at it that way!
 
On the PM-30, also has some nice features, belt drive is the real plus for me, but they’re out of stock for a while, I can wait.

As a point of reference, I ordered my PM-30 in late June, and I apparently barely missed a late July shipment. I understand that my mill is included in a shipment that has arrived at QMT (probably the same inbound shipment as @sfsteel 's new PM-30), and that my mill is being prepared to ship out now (I ordered it with DROs). I got the impression that this shipment took longer than they expected to arrive, so maybe the tariff war is getting in the way.

I’ve read of some VFD mods on the 932 but not sure I want to go down that road and don’t want to void a really nice 3-year warranty.

If I were ordering a gearhead mill or lathe, I think I would just go 3Ø and consider the VFD part of the initial acquisition cost. Does @qualitymachinetools really void warranty for adding VFD? (I never asked before because belt-driven DC makes more sense for me right now anyway.)

Also, it looks like the 932 includes X and Z power feed even without PDF, unless you back out to the "BASIC" model. I bought the PM-30 with the X power feed option, but since a Z power feed isn't available as an option for the PM-30, I guess I'll be making a shop-made Z power feed.
 
I would contact QMT as far as warranty coverage, in my discussions with them in the past (and having done numerous VFD conversions including the 932), the mechanics of the machine are still covered. QMT also sells the Hitachi WJ200 VFDs which work well, some people have also used the Teco L510 which is less expensive but doesn't support an external braking resistor. Three phase motors tend to be more reliable than single phase, in particular with frequent start/stops. A gear head will be louder vs. a belt drive. The higher RPM is a plus in softer materials (like aluminum), but if you want to remove a lot of material use a rougher endmill, you will be limited by the drive feed rate. Rigidity wise, the additional weight of the 932 is a plus, but then it depends on the work you are doing. If smaller parts, I doubt you would notice a difference between the machines. The DC drives tend to be more powerful at lower motor speeds vs. a VFD drive, but the latter can be operated at higher RPMs to give better performance (my VFD knee mill operates from 20-200 Hz). The VFD conversions I have done for 932-940 owners, a typical motor operating range is 20-75Hz, your top speed is limited by the gearbox. The stock 932 has a high speed spindle RPM of 1970, with a VFD you could push it a bit higher, maybe 2300-2400 RPM, I wouldn't want to go any higher. So the VFD is more for speed flexibility as opposed to top end speed.

Variable speed is great for dialing in the sweet spot, but you can get by with 6 fixed speeds. On the 932, I would definitely recommend a minimum of the 932M (power X and Z feeds), cranking the head gets old very quickly especially with the heavier heads. PDF, well depends if you think you are going to use it, so boils down to the type of work you are doing. I had PDF on my previous benchtop and my current knee mill, in 6+ years I have yet to use it, but if you are going to do boring, it gives a smoother finish then by hand.

Axis travel is often overlooked, it was the one major limiting factor in my previous benchtop mill, in particular the Y axis. Add a DRO scale, and a large vise any your Y travel disappears very quickly, also Z axis height/travel.

So no clear answer, either would work very well. Cost wise with X axis drives they are very close.
 
Thanks, reading through all the pluses and minuses, and past reviews, I think I’ll go with the 932 with all the options. I’ll see how I like the drive, if not there’s always the option of speaking with PM about warranties and VFD’s. I’m not a production shop, I restore vintage German cars, and parts aren’t always available. i Also want to be able to do some carburetors bores and face, warped mounting plates on 50 year old Solex carburetors (sending them out for that costs about half the price of the new machine). I made the decision to upgrade from my current small mill after finding that an axial indicator can’t be put into the spindle without removing the workpiece...kinda defeats the purpose
 
i Also want to be able to do some carburetors bores and face, warped mounting plates on 50 year old Solex carburetors (sending them out for that costs about half the price of the new machine).

Very cool, both should get the job done and be a major step up. I do like that the larger benchtop mills come with a power Z Drive, was one of the first things I built for my last mill. Please be aware the the Z axis height table to head can get eaten up very quickly, when you add the vise height, a face mill and the R8 arbor. On my setup I loose about 6" using a 6" vise, and a 4" face mill with R8 Arbor. So if you were surfacing something tall like a manifold or a head you may be limited. The PM-940M has an extra 4" of head to table height (22" vs. 18"), the motor is 2Hp vs. the 932M which is 1.5Hp, Y travel is 12" vs. 8". I always say buy once, cry once. One reason why I sold my old benchtop mill was the limited Y travel which was 8".
 
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